Reaction: L-proline betaine + a [Co(I) quaternary-amine-specific corrinoid protein] = a [methyl-Co(III) quaternary-amine-specific corrinoid protein] + N-methyl-L-proline
Glossary: L-proline betaine = (2S)-1,1-dimethylpyrrolidinium-2-carboxylate
Other name(s): mtpB (gene name)
Systematic name: L-proline betaine:[Co(I) quaternary-amine-specific corrinoid protein] Co-methyltransferase
Comments: The enzyme, characterized from the bacterium Eubacterium limosum, is a component of a system that transfers a methyl group from L-proline betaine to tetrahydrofolate, as part of an L-proline betaine degradation pathway. The resulting 5-methyltetrahydrofolate is processed to acetyl-CoA via the Wood—Ljungdahl pathway.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Picking, J.W., Behrman, E.J., Zhang, L. and Krzycki, J.A. MtpB, a member of the MttB superfamily from the human intestinal acetogen Eubacterium limosum, catalyzes proline betaine demethylation. J. Biol. Chem. 294 (2019) 13697-13707. [PMID: 31341018]